Direct answer: CONNY is a German legal-tech business that offers online checks and enforcement services for selected tenant claims, particularly claims under the Mietpreisbremse. According to CONNY’s current website, a tenant enters information about the apartment and tenancy, receives an initial assessment and can then instruct CONNY to pursue a rent reduction. CONNY describes its model as success-based, with partner lawyers handling court proceedings where necessary and considered appropriate.
Last reviewed: 23 July 2026. This independent overview is not an endorsement and has no affiliation with CONNY. Terms, eligibility and fees should be checked directly before instruction.
1. The problem CONNY is designed to address
Germany’s rent-brake rules can allow a tenant to challenge a starting rent that exceeds the statutory limit. The calculation can be difficult because it may depend on the local rent index, apartment characteristics, the previous rent, recent modernisation, new-build status and the landlord’s pre-contract disclosure.
A tenant must also take an active step: section 556g BGB requires a complaint (Rüge) before certain overpayments can be recovered. The date and content of that complaint matter. CONNY has built an online workflow around collecting the relevant facts, estimating a possible reduction and pursuing qualifying claims.
2. How CONNY says its process works
- Online data entry: the tenant provides the address, rent, contract and apartment details.
- Initial calculation: the platform estimates whether the agreed rent may exceed the permitted level.
- Instruction: the tenant decides whether to mandate CONNY. The landlord is not contacted merely because the tenant runs the initial check.
- Complaint and correspondence: CONNY states that it sends the complaint and handles communication with the landlord.
- Possible court stage: CONNY states that partner lawyers may bring a claim where an out-of-court solution is not reached and the case is considered suitable.
3. How the fee model is described
CONNY currently advertises a free initial calculation and a success-based fee model. Its website explains that the remuneration is generally funded from claims relating to past overpayments and may, in specified cases, involve a minimum fee linked to a period of future savings. The precise contract terms—not a summary on another website—govern the customer’s obligations.
4. Questions to ask before signing
| Question | Why it matters |
|---|---|
| Which claims are assigned or transferred? | The agreement may authorise CONNY to pursue and collect specified claims in its own name or through partners. |
| What is the exact fee in settlement, early success or litigation? | “No win, no fee” does not replace the need to read minimum-fee, settlement and termination clauses. |
| Who makes settlement decisions? | The tenant should know whether every settlement requires express approval. |
| Who bears court and opponent costs? | The answer should be confirmed in the current mandate terms for the specific service. |
| Which tenancy documents are required? | A reliable calculation may require the full contract, rent changes, apartment data and landlord disclosures. |
| How is personal data used? | Tenancy documents contain financial, address and sometimes household information. |
5. CONNY compared with other routes
- Direct written complaint: a tenant may prepare and send a complaint personally, but must understand the calculation and procedural consequences.
- Berlin Mietpreisprüfstelle: Berlin’s official rent-check office offers free assistance with suspected excessive rent.
- Tenant association: membership may include advice and template letters, subject to the association’s conditions and waiting periods.
- Individual lawyer: suitable where the dispute includes termination, defects, arrears, complex modernisation or strategic issues beyond the rent brake.
- Legal-expenses insurance: coverage depends on the policy, waiting periods and the date the dispute arose.
6. When an automated check is not enough
Legal-tech tools are most useful for structured, repeatable claims. A lawyer should review the wider file where the landlord threatens termination, the apartment has mixed residential/commercial use, the contract is furnished or temporary, the tenant has arrears, the facts around comprehensive modernisation are disputed, or several claims must be coordinated.
Frequently asked questions
Is CONNY a government service?
No. It is a private legal-tech provider. Berlin separately operates an official Mietpreisprüfstelle.
Does the online check itself contact the landlord?
CONNY’s current website states that the landlord is contacted only after the tenant mandates the service.
Is CONNY always the cheapest option?
That cannot be answered generally. Compare the current mandate terms with a tenant association, individual legal advice and any applicable legal-expenses insurance.